Wonder Woman, Batman, and Robin arrive at the Fortress of Solitude to celebrate Superman's birthday, but find him under the thrall of a flower called the Black Mercy, a gift from Mongul. Under its control, Superman experiences his greatest desire, life on an unexploded Krypton. While Wonder Woman fights with Mongul, Batman and Robin remove the flower from Superman, and after it briefly attaches to Batman, Robin puts it on Mongul, trapping him in dreams of his own greatest desire.